1. Field of the Invention
The present disclosure relates to server clusters. More specifically, the present disclosure relates to a method and system for determining a response plan to a hypothetical event in a computer cluster without modifying the cluster's configuration and state.
2. Related Art
A computer cluster consists of a multitude of computer nodes that work together, for instance, to host applications such as a Web service. A system administrator can deploy an application in the cluster by creating a policy that models the functional requirements of the application, and that indicates the server nodes needed by the application.
Oftentimes, the system administrator expresses the application's requirements in terms of explicit resource entities that represent the application's components, as well as the relationships and dependencies among components. For example, the policy can express a resource as a reference to a physical (a computer node, a disk, a volume, etc.) or logical (an IP address, a database instance, a database service, a server pool, etc.) entity comprising the application. Further, the policy can also indicate resource dependencies that indicate how the application's components interact with each other and with other resources in the cluster.
Once the system administrator creates a policy that models the entities used by the application, the cluster system uses this information to manage the entire application across the cluster, to provide a high availability of the application, and to facilitate scaling the application. Unfortunately, it is not always clear to the system administrator how the cluster system may use the policy to deploy the application in the cluster. It can be difficult for the system administrator to determine how the cluster may interpret the policy to react to an unforeseen event. Further, if the system administrator plans to modify an entity of the cluster (e.g., a server node or an application configuration), it can be difficult for the system administrator to determine how the planned modifications to this entity will affect the cluster as a whole.